18F-FDG-PET/CT Evaluation of Indeterminate Adrenal Masses in Noncancer Patients

Context Adrenal tumors in noncancer patients are common. Objective Evaluate performance of 18F-fluorodeoxyglucose positron emission tomography computed tomography (18F-FDG-PET/CT) in distinguishing between benign and malignant adrenal tumors. Design Retrospective chart review 2010-2019. Setting Academic institution. Patients One hundred and seventeen noncancer patients, defined as having no history of cancer or with cancer in remission for ≥5 years, completed 18F-FDG-PET/CT to evaluate adrenal masses, with pathologic diagnoses or imaging follow-up (≥12 months). Intervention 18F-FDG-PET/CT of 117 indeterminate adrenal masses. Main Outcome Measures Receiver operator characteristic curve of the ratios of adrenal lesion standardized uptake value (SUV)max to liver SUVmean and of adrenal lesion SUVmax to aortic arch blood pool SUVmean were constructed. Results Seventy benign and 47 malignant masses (35 adrenocortical carcinomas [ACCs], 12 adrenal metastases) were identified. Malignant masses had higher median liver SUV and blood pool SUV ratios than benign masses (6.2 and 7.4 vs 1.4 and 2.0, P < .001). Median liver and blood pool SUV ratios of ACC (6.1 and 7.3, respectively) and metastases (6.7 and 7.7, respectively) were higher than those of than adenomas (1.4 and 2.2, P < .05 for all comparisons). Optimal liver SUV ratio to discern between benign and malignant masses was 2.5, yielding 85% sensitivity, 90% specificity, and 7 false negative results (including 3 ACCs). Optimal blood pool SUV ratio was 3.4, yielding 83% sensitivity, 90% specificity, and 8 false negative results (including 4 ACCs). Conclusion When used in conjunction with other clinical assessments, 18F-FDG-PET/CT can be a valuable tool in evaluating adrenal masses in noncancer patients.